Introduction

NOTE: For Specifications with illustrations, make reference to SPECIFICATIONS for D379B, D398B, D399 GENERATOR SET ENGINE ATTACHMENTS, Form No. SENR2546. If the Specifications in Form SENR2546 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Woodward UG8 Governors

SCHEMATIC OF UG8 LEVER GOVERNOR

Woodward UG8 Dial And Lever Governor

The UG8 Dial Governor is a mechanical-hydraulic governor. A hydraulic activated power piston is used to turn the output terminal shaft of the governor. A lever on the terminal shaft is connected to the fuel rack by a linkage rod. The governor has a separate oil supply and oil pump. The governor oil pump and ballhead are driven from a shaft in the governor drive housing. The shaft is driven by the fuel pump drive shaft.

The oil pump gives pressure oil to operate the power piston. The drive gear of the oil pump has a bushing in which the pilot valve plunger moves up and down. The driven gear of the oil pump is also the drive for the ballhead.

An accumulator is used to keep a constant oil pressure of approximately 120 psi (830 kPa) to the top of the power piston and to the pilot valve.

The power piston is connected by a lever to the output terminal shaft. There is oil pressure on both the top and bottom of the power piston. The bottom of the piston has a larger area than the top.

Less oil pressure is required on the bottom than on the top to keep the piston stationary. When the oil pressure is the same on the top and bottom of the piston, the piston will move up and cause the output terminal shaft to turn in the increase fuel direction. When oil pressure on the bottom of the piston is directed to the sump, the piston will move down and cause the output terminal shaft to turn in the decrease fuel direction. Oil to or from the bottom of the power piston is controlled by the pilot valve.

The pilot valve has a pilot valve plunger and a bushing. The bushing is turned by the governor drive shaft. The rotation of the bushing helps reduce friction between the bushing and the plunger. The pilot valve plunger has a land that controls oil flow through the ports in the bushing. When the pilot valve plunger is moved down, high pressure oil goes to the bottom of the power piston and the power piston will move up. When the pilot valve plunger is moved up, the oil on the bottom of the power piston is released to the sump and the power piston moves down. When the pilot valve plunger is in the center (balance) position, the oil port to the bottom of the power piston is closed and the power piston will not move. The pilot valve plunger is moved by the ballhead assembly.

SCHEMATIC OF UG8 DIAL GOVERNOR

The ballhead assembly has a ballhead, flyweights, speeder spring, thrust bearing, speeder plug, and speeder rod. The ballhead assembly is driven by a gear and shaft from the driven gear of the oil pump. The speeder rod is fastened to the thrust bearing which is on the toes of the flyweights. The speeder rod is connected to the pilot valve plunger with a lever. The speeder spring is held in position on the thrust bearing by the speeder plug.

As the ballhead turns, the flyweights move out due to centrifugal force. This will make the flyweight toes move up and cause compression of the speeder spring. When the force of the speeder spring and the force of the flyweights are equal the engine speed is constant. The speeder plug can be moved up or down manually to change the compression of the speeder spring and will change the speed of the engine.

The compensation system gives stability to engine speed changes. The compensation system has a needle valve and two pistons - an actuating piston and a receiving piston. The actuating piston is connected to the output terminal shaft by the compensation adjusting lever. A fulcrum that is adjustable is on the lever. When the position of the fulcrum is changed, the amount of movement possible of the actuating piston is changed.

The receiving piston is connected to the pilot valve plunger and the speeder rod by a lever.

The needle valve makes a restriction to oil flow between the oil sump and the two pistons.

When the actuating piston moves down, the piston forces the oil under the receiving piston and moves it up. When the receiving piston moves up it raises the pilot valve plunger to stop the flow of oil to the bottom of the power piston.

When the engine is in operation at a steady speed the land on the pilot control valve is in the center of the control port of the bushing. A decrease in load will cause an increase in engine speed. With an increase in engine speed the flyweights move out and raise the speeder rod and floating lever. This raises the pilot valve plunger and releases oil from the bottom of the power piston. As the power piston moves down the output terminal shaft moves in the decrease fuel direction. When the output terminal shaft moves, the actuating compensation piston moves up and causes a suction on the receiving piston which moves down. The floating lever is pulled down by the receiving piston and the lever moves the pilot control valve down to close the control port. The outpu terminal shaft and power piston movement is stopped. As the engine speed returns to normal the flyweights move in and the speeder rod moves down. When the oil pressure in the compensation system and the sump oil become the same through the needle valve, the receiving compensation piston moves up at the same rate as the speeder rod moves down. This action keeps the pilot valve plunger in position to close the port.

An increase in load will cause a decrease in engine speed. When engine speed decreases, the flyweights move in and lower the speeder rod and floating lever. This lowers the pilot valve plunger and lets pressure oil go under the power piston. The power piston moves up and turns the output terminal shaft in the increase fuel direction. When the output terminal shaft moves, the actuating compensation piston moves down and causes a pressure on the receiving piston which moves up. The floating lever is pushed up by the receiving piston and the lever moves the pilot valve plunger up to close the control port. The output terminal shaft and power piston movement is stopped.

A change to the speed setting of the governor will give the same governor movements as an increase or decrease in load.

UG8 Lever Governor

A lever on the speed adjustment shaft is used to change the engine speed. The speed adjustment shaft moves the speeder plug up and down to change the force of the speeder spring.

This governor is equipped with speed droop, however, it must be adjusted inside the governor.

UG8 Dial Governor

The synchronizer is used to change engine speed. The speed setting motor on the top of the governor can also be used to change engine speed. Either control turns the speeder plug which moves up or down and changes the force of the speeder spring. The synchronizer indicator gives an indication of the number of turns the synchronizer has moved.

The load limit control is used to control the amount of travel of the output terminal shaft. The control can be used to stop the engine if the knob is turned to zero.

The speed droop control is used to adjust the amount of speed droop from zero to one hundred percent. Speed droop is the difference between no load high idle rpm and full load rpm. This difference in rpm divided by the full load rpm and multiplied by 100 is the percent of speed droop.

UG8 DIAL GOVERNOR
1. Speed droop knob. 2. Synchronizer knob. 3. Load limit knob. 4. Synchronizer indicator.

Zero speed droop is used on a single system engine, such as a standby generator set. Speed droop higher than zero permits a load to be divided between two or more engines connected to the same load.

Air Fuel Ratio Control

SCHEMATIC OF AIR FUEL RATIO CONTROL SYSTEM

The air fuel ratio control is installed on top of the basic UG8L Governor. The unit is made up of an inlet manifold pressure sensor, a hydraulic circuit and mechanical linkage that connects the unit to the governor. Pressure oil from the governor hydraulic system is used to operate the unit.

When engine speed or load is increased rapidly it is possible for a standard (unlimited) governor to supply more fuel than can be burned with the amount of available air. Too much smoke and a poor acceleration are the result. The fuel ratio control works to limit the movement of the governor terminal shaft in the increase fuel direction as a direct result of inlet manifold pressure. Thus, fuel which can be burned is limited to the air available for combustion as the engine speed is increased. This gives more complete combustion and keeps smoke to a minimum while acceleration is improved.

The air fuel ratio is also used for protection to limit the fuel as the result of any large, sudden restriction of air supply to the engine.

Governor accumulator oil pressure is changed to a restricted variable (pulsating) oil flow as small holes (ports) in the pilot valve bushing move past a passage in the controlet housing. In a constant speed operation, the ball valve is not tight against its seat and lets oil flow back to the sump. The ball valve is held in position by the sensing bellows, which is connected to inlet manifold air pressure. The force used to hold the ball valve is proportional to the inlet manifold air pressure.

As inlet manifold air pressure increases the ball valve makes contact with its seat and oil pressure increases to move the limiter piston to the right against the force of the restoring spring. This movement increases the tension on the restoring spring until the spring force is in balance with the sensing bellows force. The oil pressure now can push the ball valve off its seat and let a small amount of oil flow to the sump. This reduces the pressure behind the limiter piston and the piston stops movement. The piston position is proportional to inlet manifold air pressure.

The cam fastened to the limiter piston operates through linkage to limit the travel of the governor terminal shaft. The governor terminal shaft limits the fuel to the engine through the fuel control linkage. The terminal shaft can turn in the increase fuel direction until the pivot lever lifts the pilot valve above center. Oil pressure on the bottom of the power piston is now directed to the sump. The power piston moves down and causes the terminal shaft to turn in the decrease fuel direction.

When the engine is stopped, the limiter piston is held to the left by the restoring spring. The fuel limit valve at this position is set high enough by the cam to give enough fuel for start up. At cranking speed, oil pressure behind the limiter piston goes by the diaphram to the sump. After the engine has started, engine lubrication oil pressure pushes the diaphram against its seat and closes the governor oil drain. Oil pressure now increases behind the limiter piston. The limiter piston moves out until the roller follower is on the operating slope of the cam. At this point the ball valve is moved off its seat, the oil can now flow to sump and the piston movement is stopped.

Air Starting System

The air starting motor is used to turn the engine flywheel fast enough to get the engine running.

AIR STARTING SYSTEM (TYPICAL EXAMPLE)
1. Starter control valve. 2. Oiler. 3. Relay valve. 4. Air starting motor.

The air starting motor can be mounted on either side of the engine. Air is normally contained in a storage tank and the volume of the tank will determine turning time of engine. The storage tank must hold this volume of air at 250 psi (1720 kPa) when filled.

For engines which do not have heavy loads when starting, the regulator setting is approximately 100 psi (690 kPa). This setting gives a good relationship between cranking speeds fast enough for easy starting and the length of time the air starting motor can turn the engine before the air supply is gone.

If the engine has a heavy load which can not be disconnected during starting, the setting of the air pressure regulating valve needs to be higher in order to get high enough speed for easy starting.

The air consumption is directly related to speed. The air pressure is related to the effort necessary to turn the engine flywheel. The setting of the air pressure regulator can be up to 150 psi (1030 kPa) if necessary to get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine as fast as it can turn a lightly loaded engine.

Other air supplies can be used if they have the correct pressure and volume. For good life of the air starting motor, the supply should be free of dirt and water. The maximum pressure for use in the air starting motor is 150 psi (1030 kPa). Higher pressures can cause safety problems.

The 1L5011 Regulating and Pressure Reducing Valve Group has the correct characteristics for use with the air starting motor. Most other types of regulators do not have the correct characteristics. Do not use a different style of valve in its place.

AIR STARTING MOTOR (Ingersoll-Rand Motor Shown)
5. Vanes. 6. Rotor. 7. Air inlet. 8. Pinion. 9. Gears. 10. Piston. 11. Piston spring.

The air from the supply goes to relay valve (3). The starter control valve (1) is connected to the line before the relay valve (3). The flow of air is stopped by the relay valve (3) until the starter control valve (1) is activated. Then air from the starter control valve (1) goes to the piston (10) behind the pinion (8) for the starter. The air pressure on the piston (10) puts the spring (11) in compression and puts the pinion (8) in engagement with the flywheel gear. When the pinion is in engagement, air can go out through another line to the relay valve (3). The air activates the relay valve (3) which opens the supply line to the air starting motor.

The flow of air goes through the oiler (2) where it picks up lubrication oil for the air starting motor.

The air with lubrication oil goes into the air motor. The pressure of the air pushes against the vanes (5) in the rotor (6). This turns the rotor which is connected by gears (9) to the starter pinion (8) which turns the engine flywheel.

When the engine starts running the flywheel will start to turn faster than the starter pinion (8). The pinion (8) retracts under this condition. This prevents damage to the motor, pinion (8) or flywheel gear.

When the starter control valve (1) is released, the air pressure and flow to the piston (10) behind the starter pinion (8) is stopped. The piston spring (11) pulls back the pinion (8). The relay valve (3) stops the flow of air to the air starting motor.

Electrical System

The electrical system can have three separate circuits: the charging circuit, the starting circuit and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits.

The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.

The starting circuit is in operation only when the start switch is activated.

The starting circuit can have a glow plug for each cylinder of the diesel engine. Glow plugs are small heating units in the precombustion chambers. Glow plugs make ignition of the fuel easier when the engine is started in cold temperature.

The low amperage circuit and the charging circuit are both connected to the same side of the ammeter. The starting circuit connects to the opposite side of the ammeter.

Charging System Components

Alternator (Delco-Remy)

The alternator is driven by V-type belts from a pulley on the accessory drive. This alternator is a three phase, self-rectifying charging unit, and the regulator is part of the alternator.

This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are: the field winding, stator windings, six rectifying diodes, and the regulator circuit components.

The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of the current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent on to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.

The voltage regulator is a solid state (transistor stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

5S9088 DELCO-REMY ALTERNATOR
1. Regulator. 2. Roller bearing. 3. Stator winding. 4. Ball bearing. 5. Rectifier bridge. 6. Field winding. 7. Rotor assembly. 8. Fan.

Starting System Components

Starter Motor

The starter motor is used to turn the engine flywheel fast enough to get the engine running.

The starter motor has a solenoid. When the start switch is activated, electricity from the electrical system will cause the solenoid to move the starter pinion to engage with the ring gear on the flywheel of the engine. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the start switch is released, the starter pinion will move away from the ring gear of the flywheel.

STARTER MOTOR
1. Field. 2. Solenoid. 3. Clutch. 4. Pinion. 5. Commutator. 6. Brush assembly. 7. Armature.

Solenoid

A solenoid is a magnetic switch that uses low current to close a high current circuit. The solenoid has an electromagnet with a core (6) which moves.

SCHEMATIC OF A SOLENOID
1. Coll. 2. Switch terminal. 3. Battery terminal. 4. Contacts. 5. Spring. 6. Core. 7. Component terminal.

There are contacts (4) on the end of core (6). The contacts are held in the open position by spring (5) that pushes core (6) from the magnetic center of coil (1). Low current will energize coil (1) and make a magnetic field. The magnetic field pulls core (6) to the center of coil (1) and the contacts close.

Magnetic Switch

A magnetic switch (relay) is used sometimes for the starter solenoid or glow plug circuit. Its operation electrically, is the same as the solenoid. Its function is to reduce the low current load on the start switch and control low current to the starter solenoid or high current to the glow plugs.

Other Components

Circuit Breaker

The circuit breaker is a safety switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker.

A heat activated metal disc with a contact point completes the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset after it cools. Push the reset button to close the contacts and reset the circuit breaker.

CIRCUIT BREAKER SCHEMATIC
1. Reset button. 2. Disc in open position. 3. Contacts. 4. Disc. 5. Battery circuit terminals.

Wiring Diagrams

Many types of electrical systems are available for these engines. Some charging systems use an alternator and a regulator in the wiring circuit. Others have the regulator inside the alternator. Some starting systems have one starter motor. Engines which must operate in bad starting conditions can have two starter motors. Other starting systems use air or hydraulic motors.

Glow plugs are provided for low temperature starting conditions. Systems without glow plugs are usually used where ideal starting conditions exist or where an Automatic Start-Stop system is used.

A fuel or oil pressure switch is used in all systems with an external regulator. The switch prevents current discharge (field excitation) to alternator from the battery when the engine is not in operation. In systems where the regulator is part of the alternator, the transistor circuit prevents current discharge to the alternator and the fuel or oil pressure switch is not required.

All wiring schematics are usable with 12, 24, 30 or 32 volts unless the title gives a specific description.

NOTE: Automatic Start-Stop systems use different wiring diagrams.

The chart gives the correct wire sizes and color codes. Make reference to the description in Systems Operation for the function of each of the components.

TACHOMETER WIRING DIAGRAM
1. Tachometer. 2. Sending Unit. 3. TS1.

Grounded Electrical Systems (Regulator Inside Alternator)

STARTING SYSTEM WITH TWO ELECTRIC STARTER MOTORS
1. Magnetic switch. 2. Start switch. 3. Battery. 4. Starter motors.

STARTING SYSTEM WITH TWO ELECTRIC STARTER MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Battery. 5. Starter motors.

Insulated Electrical Systems (Regulator Inside Alternator)

STARTING SYSTEM WITH TWO ELECTRIC STARTER MOTORS
1. Magnetic switch. 2. Start switch. 3. Battery. 4. Starter motors.

STARTING SYSTEM WITH TWO ELECTRIC STARTER MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Battery. 5. Starter motors.

(Regulator Inside Alternator)

STARTING SYSTEM WITH ELECTRIC STARTER MOTOR
1. Start switch. 2. Battery. 3. Starter motor.

STARTING SYSTEM WITH ELECTRIC STARTER MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Battery. 5. Starter motor.

(Regulator Inside Alternator)

STARTING SYSTEM WITH ELECTRIC STARTER MOTOR
1. Start switch. 2. Battery. 3. Starter motor.

STARTING SYSTEM WITH ELECTRIC STARTER MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Battery. 5. Starter motor.

(Regulator Inside Alternator)

CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Alternator.

(Regulator Inside Alternator)

CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Alternator.

(Regulator Inside Alternator)

CHARGING SYSTEM WITH ELECTRIC STARTER MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starter motor.

CHARGING SYSTEM WITH ELECTRIC STARTER MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starter motor. 7. Alternator.

(Regulator Inside Alternator)

CHARTING SYSTEM WITH ELECTRIC STARTER MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starter motor.

CHARGING SYSTEM WITH ELECTRIC STARTER MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starter motor. 7. Alternator.

(Regulator Inside Alternator)

CHARGING SYSTEM WITH TWO ELECTRIC STARTER MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter 4. Battery. 5. Starter motors. 6. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTER MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starter motors. 7. Alternator.

(Regulator Inside Alternator)

CHARGING SYSTEM WITH TWO ELECTRIC STARTER MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter 4. Battery. 5. Starter motors. 6. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTER MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starter motors. 7. Alternator.

(Prelubrication Pump)

230-AC PRELUBRICATION PUMP
1. Oil pressure switch. 2. Start switch. 3. Magnetic switch. 4. 230-AC Prelubrication pump. 5. Battery. 6. Starter motor. 7. Relay.

24-30-32 V-DC PRELUBRICATION PUMP
1. Oil pressure switch. 2. Start switch. 3. Magnetic switch. 4. 24-30-32 V-DC Prelubrication pump. 5. Battery. 6. Starter motor.

(Prelubrication Pump)

230V-AC PRELUBRICATION PUMP
1. Oil pressure switch. 2. Start switch. 3. Magnetic switch. 4. 230V-AC Prelubrication pump. 5. Battery. 6. Starter motor. 7. Relay.

24-30-32 V-DC PRELUBRICATION PUMP
1. Oil pressure switch. 2. Start switch. 3. Magnetic switch. 4. 24-30-32 V-DC Prelubrication pump. 5. Battery. 6. Starter motor.

Shutoff And Alarm Systems

Alarm Contactor System

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Source voltage. 4. Toggle switch (optional). 5. Alarm. 6. Signal lights.

If the oil is too low or the water temperature is too high this system will activate alarm (5) and signal lights (6).

Before the engine is started it will be necessary to override the oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the oil pressure switch or toggle switch (4). Oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine has oil pressure.

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Air temperature contactor. 4. Source voltage. 5. Signal lights (three). 6. Toggle switch (optional).

If the oil pressure is too low or the water temperature is too high this system will activate signal lights (5).

Before the engine is started it will be necessary to override the oil pressure switch (1) or the signal lights will activate. This is done by either a manual override button on the oil pressure switch or toggle switch (6). Oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine has oil pressure.

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Air temperature contactor. 4. Source voltage. 5. Alarm. 6. Toggle switch (optional).

If the oil pressure is too low or the water temperature is too high this system will activate alarm (5).

Before the engine is started it will be necessary to override the oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the oil pressure switch or toggle switch (6). Oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine has oil pressure.

Water Temperature And Oil Pressure Shutoff System

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Oil pressure (time delay) or fuel pressure switch. 4. Rack solenoid. 5. Diode assembly. 6. Starter. 7. Battery.

If the oil pressure is too low or the water temperature is too high this system will activate rack solenoid (4). The solenoid is connected to the fuel rack by linkage. When it is activated it will move to stop the flow of fuel to the engine. The engine will stop.

Before the engine can be started it will be necessary to push the manual override button on oil pressure switch (1). Oil pressure will return the manual override button to the run position.

Diode assembly (5) is used to stop arcing, for protection of the system.

Oil pressure delay or fuel pressure switch (3) is used to prevent discharge of battery (7) through the solenoid when the engine is stopped. The optional grounds to engine shown are used with grounded systems only.

Water Temperature, Oil Pressure And Electronic Overspeed With Air Shutoff

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override button shown). 2. Water temperature contactor. 3. Oil pressure (time delay) or fuel pressure switch. 4. Overspeed switch. 5. Diode. 6. Air shutoff solenoids. 7. Rack solenoid. 8. Diode assemblies. 9. Magnetic pickup. 10. Starter. 11. Battery.

This system gives high water temperature, low oil pressure and overspeed protection. See WATER TEMPERATURE, OIL PRESSURE AND ELECTRONIC OVERSPEED SYSTEM.

Diode assemblies (8) are used to stop arcing, for protection of the system.

Diode (5) keeps the air shutoff solenoid circuit separate from the rack shutoff solenoid circuit. The air shutoff solenoid can only be activated by the electronic speed switch. If the signal to shutoff the engine comes from any other component only the rack solenoid will activate.

NOTE: If the air shutoff solenoid has been activated it will be necessary to reset the valve assembly before the engine can be started.

Shutoff And Alarm System Components

Oil Pressure Switch

Micro Switch Type

The oil pressure switch is used to give protection to the engine from damage because of low oil pressure. When oil pressure lowers to the pressure specifications of the switch, the switch closes and activates the rack shutoff solenoid.

On automatic start/stop installations, this switch closes to remove the starting system from the circuit when the engine is running with normal oil pressure.

This switch for oil pressure can be connected in a warning system for indication of low oil pressure with a light or horn.

As pressure of the oil in bellows (6) becomes higher, arm (4) is moved against the force of spring (3). When projection (10) of arm (4) makes contact with arm (9), pressure in the bellows moves both arms. This also moves button (8) of the micro switch to activate the micro switch.

OIL PRESSURE SWITCH (Micro Switch Type)
1. Locknut. 2. Adjustment screw. 3. Spring. 4. Arm. 5. Spring. 6. Bellows. 7. Latch plate. 8. Button for micro switch. 9. Arm. 10. Projection of arm.

Some of these switches have a "Set For Start" button. When the button is pushed in, the micro switch is in the START position. This is done because latch plate (7) holds arm (9) against button (8) of the micro switch and the switch operates as if the oil pressure was normal. When the engine is started, pressure oil flows into bellows (6). The bellows move arm (4) into contact with latch plate (7). The latch plate releases the "Set For Start" button and spring (5) moves it to the RUN position. This puts the switch in a ready to operate condition.

Pressure Switch

These type pressure switches are used for several purposes and are available with different specifications. They are used in the oil system and in the fuel system. One use of the switch is to open the circuit between the battery and the rack shutoff solenoid after the oil pressure is below the pressure specifications of the switch. It also closes when the engine starts.

Another use of the switch is to close and activate the battery charging circuit when the pressure is above the pressure specification of the switch. It also disconnects the circuit when the engine is stopped.

PRESSURE SWITCH

Some switches of this type have three terminal connections. They are used to do two operations with one switch. They open one circuit and close another with the single switch.

Shutoff Solenoid

A shutoff solenoid changes electrical input into mechanical output. It is used to move a valve assembly in the air inlet pipe to a closed position. This stops the engine.

The shutoff solenoid can be activated by any one of the many sources. The most usual are: water temperature contactor, oil pressure switch, overspeed switch and remote manual control switch.

RACK SHUTOFF SOLENOID (Typical Illustration)

Water Temperature Contactor Switch

The contactor switch for water temperature is installed in the water manifold. No adjustment to the temperature range of the contactor can be made. The element feels the temperature of the coolant and then operates the micro switch in the contact when the coolant temperature is too high, the element must be in contact with the coolant to operate correctly. If the cause for the engine being too hot is because of low coolant level or no coolant, the contactor switch will not operate.

The contactor switch is connected to the rack shutoff solenoid to stop the engine. The switch can also be connected to an alarm system. When the temperature of the coolant lowers to the operating range, the contactor switch opens automatically.

WATER TEMPERATURE CONTACTOR SWITCH

Circuit Breaker

The circuit breaker gives protection to an electrical circuit. Circuit breakers are rated as to how much current they will permit to flow. If the current in a circuit gets too high it will cause heat in disc (3). Heat will cause distortion of the disc and contacts (2) will open. No current will flow in the circuit.

An open circuit breaker will close (reset) automatically when it becomes cooler.

CIRCUIT BREAKER SCHEMATIC
1. Disc in open position. 2. Contacts. 3. Disc. 4. Circuit terminals.

Electronic Speed Switch

The electronic speed switch (dual speed switch) activates the shutoff solenoid when the engine speed gets approximately 18% higher than the rated full load speed of the engine. It also causes the starter motor pinion to move away from the flywheel.

The electronic speed switch makes a comparison between the output frequency of the magnetic pickup and the setting of the electronic speed switch. When they are equal, the normally open contacts in the electronic speed switch close. Lamp (2) will go on. The switch also has a fail safe circuit that will cause the engine to shutdown if there is an open in the magnetic pickup circuit.

When the engine is stopped it will be necessary to push reset button (1), before the engine can be started.

ELECTRONIC SPEED SWITCH
1. Reset button. 2. Lamp.

Hydramechanical Protective System

There are two hydra-mechanical shutoffs used on V-8, V-12 and V-16 engines. The 5N5993 Shut-off is used on V-8, V-12 and V-16 engines with a rated speed of 900 thru 1000 rpm. The 5N5994 Shutoff is used on V-8, V-12 and V-16 engines with rated speeds of 1001 thru 1300 rpm. There is a part number identification plate attached to each unit.

NOTE: V-8 and V-12 engines have a manually operated valve located at the starter control to prevent engine shutdown when a warm engine is started. When the valve is activated at start-up, a valve in the rack circuit opens, and prevents rack actuator from moving. When the engine starts and the engine oil pressure is normal, the valve is released and the rack circuit is returned to normal operation.

Hydra-Mechanical Shutoff (5N5993 and 5N5994)

The hydra-mechanical shutoff gives protection for low oil pressure, high coolant temperature, and engine overspeed. The shutoff also has a manual control to stop the engine. The shutoff uses lubrication oil from the engine and has an oil pump to give pressure to the shutoff system.

The fuel rack shutoff will move the rack to the fuel off position with either low oil pressure or high coolant temperature. Both the fuel rack and inlet air shutoffs will activate when the engine overspeeds or if the manual control is used. The fuel rack shutoff will reset automatically but the inlet air shutoff must be manually reset.

The hydra-mechanical shutoff gives two ranges of engine oil pressure protection. As engine speed increases, the minimum oil pressure needed also increases. At low engine speed, the shutoff will activate at a minimum oil pressure of 20 psi (140 kPa). At high engine speeds, the shutoff will activate at a minimum oil pressure of 30 psi (205 kPa).

A flyweight controlled, speed sensing spool valve (1) is used to feel engine speed. This provides the two ranges of oil pressure protection and overspeed protection. The speed sensing spool valve (1) is moved by flyweights (2) which are turned by drive shaft (3). The drive shaft is connected to the engine oil pump drive shaft. When engine speed increases, the flyweights move out and push the speed sensing spool valve.

HYDRA-MECHANICAL SHUTOFF
1. Speed sensing spool valve. 2. Flyweights. 3. Drive shaft.

Hydraulic Circuits

Make reference to the schematics for the explanation that follows of the hydramechanical protective system hydraulic circuits. The hydraulic circuits inside the heavy dashed lines are in the basic shutoff group. The components outside the heavy dashed lines are lines, valves and actuators located on the engine away from the shutoff unit.

SCHEMATIC NO. 1 (HYDRAMECHANICAL PROTECTIVE SYSTEM)
1. Selector valve. 2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 5. Engine oil pressure orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 9. Thermostatic pilot valve. 10. High speed oil protection valve. 11. Emergency manual shutoff valve. 12. Air inlet shutoff actuator. 13. Air inlet sequence valve. 14. Pilot operated two-way valve. 15. Rack sequence valve. 16. Air inlet shutoff valve. 17. Oil pump. 18. Oil pressure relief valve.

SHUTOFF CONTROL GROUP
1. Selector valve. 2. Low speed oil protection valve. 6. Speed sensing valve spool. 10. High speed oil protection valve. 11. Emergency manual shutoff valve. 17. Oil pump. 18. Oil pressure relief valve. 19. Spring for overspeed adjustment. 20. Valve spool (not used). 21. Speeder spring. 22. Flyweights. 23. Pressure control valve which consists of: the rack and air inlet sequence valves, the two-way pilot operated valve and emergency manual shutoff valve (11).

Oil Pressure Protection

As engine speed increases, the required oil pressure for main bearing protection increases. The engine oil pump is a positive displacement type, therefore, engine oil pressure varies in direct proportion to speed until the pump goes on controlled bypass.

FIGURE 1 TWO-STEP PRESSURE PROTECTION

From Figure 1, it can be seen that if only the low range pressure protection level was used for the full speed range, the engine would not be protected at rated speed. Conversely, if only the high range pressure protection level was used for full speed range, the engine would be shutdown at low idle, since the engine oil pump develops lower pressure at that speed. Therefore, the protective system must operate between the required oil pressure curve and the engine oil pressure curve. This is accomplished by a step function of pressure versus speed.

SCHEMATIC NO. 2. (LOW OIL PRESSURE PROTECTION)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 10. High speed oil protection valve. 15. Rack sequence valve. 17. Oil pump.

Low Speed Range (Normal Operation)

Make Reference to Schematic No. 2

Oil flows from pump (17) to rack sequence valve (15). This is a pressure control valve that controls the pressure in the rack circuit at 110 psi (760 kPa). The remainder of the oil is sent through the air inlet circuit and then to drain. The rack circuit oil will flow through diverter valve (7) and diverter valve orifice (4). The oil flows through spool valves (2) and (1), and then to drain. Most of the air inlet circuit has been left out since it is not directly in use at this point. Engine oil pressure is not high enough to move the valve spool against the force of the spring of valve (10). Valve (10) is used in the high speed range.

SCHEMATIC NO. 3. (LOW OIL PRESSURE FAULT)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 10. High speed oil protection valve. 15. Rack sequence valve. 17. Oil pump.

Low Speed Range (Oil Pressure Fault)

Make Reference to Schematic No. 3

If the engine oil pressure goes below 20 psi (140 kPa), the spring force on valve (2) will close the valve. The oil flow in the circuit is then blocked and cannot flow to drain. The pressure of the oil will become equal on both sides of diverter valve orifice (4). Spring force will move the valve spool of diverter valve (7) down so that there is alignment with the passage that leads to rack shutoff actuator (8). Oil pressure will now move the rack shutoff actuator, which will move the rack to the "OFF" position.

SCHEMATIC NO. 4 (LOW OIL PRESSURE PROTECTION)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 10. High speed oil protection valve. 12. Air inlet shutoff actuator. 13. Air inlet sequence valve. 14. Pilot operated two-way valve. 15. Rack sequence valve. 16. Air inlet shutoff valve. 17. Oil pump. 18. Oil pressure relief valve.

High Speed Range (Normal Operation)

Make Reference to Schematic No. 4

At approximately 70% of engine full load speed, the oil pressure protection changes from the low speed range to the high speed range.

When the engine speed increases to the high speed range, speed sensing valve spool (6) will be moved up by the flyweights. This will send pilot oil to selector valve (1). This will close valve (1) and will remove low speed oil pressure protection valve (2) from the circuit. The oil must now flow through high speed oil pressure protection valve (10) to return to the sump through valve (14).

SCHEMATIC NO. 5 (LOW OIL PRESSURE FAULT)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 10. High speed oil protection valve. 15. Rack sequence valve. 17. Oil pump.

High Speed Range (Low Oil Pressure Fault)

Make Reference to Schematic No. 5

When engine oil pressure decreases to 30 psi (205 kPa), the spring force on valve (10) will move the valve spool to stop oil flow to the sump. The difference in oil pressure across diverter valve orifice (4) will now go to zero. The valve spool of diverter valve (7) will move down by spring force, which will cause alignment of the ports to the fuel rack actuator. The fuel rack will now move to the "OFF" position.

SCHEMATIC NO. 6 (HIGH COOLANT TEMPERATURE PROTECTION) (Low Speed Range Shown)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 7. Diverter valve. 8. Rack shutoff actuator. 9. Thermostatic pilot valve. 10. High speed oil protection valve. 15. Rack sequence valve.

High Coolant Temperature Protection

Make Reference to Schematic No. 6

Coolant temperature protection is in both the low and high speed ranges. The schematic shown is of the low speed range with the high coolant temperature protection circuit added. The temperature is normal and thermostatic pilot valve (9) is closed.

NOTE: The sensor of the thermostatic pilot valve (9) (water temperature shutoff valve) must be below the water level in the coolant manifold to operate.

SCHEMATIC NO. 7 (HIGH COOLANT TEMPERATURE FAULT)
1. Selector valve. 2. Low oil protection valve. 4. Diverter valve orifice. 7. Diverter valve. 8. Rack shutoff actuator. 9. Thermostatic pilot valve. 10. High speed oil protection valve. 15. Rack sequence valve.

High Coolant Temperature Fault

Make Reference to Schematic No. 7

When coolant temperature increases to 210°F (99°C), thermostatic pilot valve (9) will open. This will let oil in the circuit drain and cause a decrease in engine oil pressure at valves (2) and (10). Valves (2) and (10) will close and stop oil flow. The difference in oil pressure across diverter valve orifice (4) will now go to zero. The valve spool of diverter valve (7) will move down by spring force, which will cause alignment of the ports to the fuel rack actuator. The fuel rack will move to the "OFF" position. The engine will now be shut off by the rack shutoff actuator (8).

SCHEMATIC NO. 8 (OVERSPEED CIRCUIT)
1. Selector valve. 2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 5. Engine oil pressure orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 9. Thermostatic pilot valve. 10. High speed oil protection valve. 11. Emergency manual shutoff valve. 12. Air inlet shutoff actuator. 13. Air inlet sequence valve. 14. Pilot operated two-way valve. 15. Rack sequence valve. 16. Air inlet shutoff valve. 17. Oil pump. 18. Oil pressure relief valve.

Overspeed Protection

If the engine overspeeds to a speed 18% above full load speed the shutoff control will activate and shut off both the fuel and air supply to the engine. The air inlet shutoff must be manually reset before the engine is started again.

Overspeed Circuit (Normal Operation)

Make Reference to Schematic No. 8

Oil goes from oil pump (17) to rack sequence valve (15). Valve (15) keeps oil pressure at the start of the rack circuit at 110 psi (760 kPa). The remainder of the oil goes to air inlet sequence valve (13) and to air inlet shutoff actuator (12). Valve (13) keeps the oil pressure at the start of the air inlet circuit at 15 psi (105 kPa). The remainder of the oil goes through valve (14), which is normally open, to the sump.

NOTE: Low oil pressure or high coolant temperature conditions do not change the oil flow in the air inlet circuit.

SCHEMATIC NO. 9 (OVERSPEED FAULT)
1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 12. Air inlet shutoff actuator. 13. Air inlet sequence valve. 14. Pilot operated two-way valve. 15. Rack sequence valve. 18. Oil pressure relief valve.

Overspeed Circuit (Overspeed Fault)

Make Reference to Schematic No. 9

When the engine speed is 18% above full load speed, speed sensing valve spool (6) will be moved up by the flyweights. This will send oil to valve (14) and to the spring side of air inlet sequence valve (13). The oil pressure will close both valves and will not permit oil in the air inlet system to return to the sump. The oil pressure in the system will increase until oil pressure relief valve (18) opens at 250 psi (1720 kPa). The increased pressure will move air inlet shutoff actuator (12), which will release the air inlet shutoff valve. This stops the air supply to the engine. Rack circuit oil will also not return to the sump. The difference in oil pressure across diverter valve orifice (4) will now go to zero. The valve spool of diverter valve (7) will move down by spring force, which will cause alignment of the ports to the fuel rack actuator. The fuel rack will move to the "OFF" position. The blocked oil pressure in the rack circuit will move rack shutoff actuator (8), which will move the fuel rack to the fuel "OFF" position.

SCHEMATIC NO. 10 (EMERGENCY MANUAL SHUTOFF)
4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shutoff actuator. 11. Emergency manual shutoff valve. 13. Air inlet sequence valve. 14. Pilot operated two-way valve. 15. Air inlet sequence valve. 18. Oil pressure relief valve.

Emergency Manual Shutoff

Make Reference to Schematic No. 10

The emergency manual shutoff simulates an overspeed fault condition (refer to Schematic No. 9). When the knob on the emergency shutoff is pulled, pump flow is directed to pilot operated two-way valve (14). Valve (14) blocks the return to sump of both the rack and air inlet shutoff circuits. The rest of the sequence is the same as for an overspeed condition. The fuel rack is moved to the shutoff position and the combustion air supply is control linkage terminated.

SCHEMATIC NO. 11 (START-UP OVERRIDE)
2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 7. Diverter valve. 8. Rack shutoff actuator. 15. Rack sequence valve.

Start-Up Override Of Oil Pressure Protection

Make Reference to Schematic No. 11

On a hot restart, after severe operating conditions, the engine oil pressure is relatively slow to build up. If the rate of pressure rise is too slow, the protective system senses this as a fault condition and moves the fuel rack to the shutoff position. Therefore, an override of the low oil pressure protective circuit is included in the protective system (refer to Schematic No. 11).

Depending on the type of starter motor used, a solenoid or a start-up override valve (3) is installed in the diverter valve return line. The valve is normally closed. When valve (3) is energized, the outlet of the diverter valve is connected to drain. This maintains a pressure drop across orifice (4) and does not let the diverter valve shift to the shutdown position.

When valve (3) is de-energized, the oil protection circuit is restored.

SCHEMATIC NO. 12 (REMOTE NORMAL SHUT-OFF)
4. Diverter valve orifice. 7. Diverter valve. 8. Rack shut-off actuator. 19. Remove normal shut-off valve.

Remove Normal Shut-Off

Make Reference to Schematic No. 12

An air or electric operated remote normal shut-off valve (19) is installed in the diverter valve return line. When valve (19) is operated, the outlet of the diverter valve is blocked. The oil pressure becomes equal on both sides of orifice (4). Spring force will move the valve spool of diverter valve (7) to make an alignment of the oil passage with the oil line to fuel rack shut-off actuator (8). Oil pressure can now move the fuel rack shut-off actuator, which will move the fuel rack control linkage to the "OFF" position.

Hydraulic Circuits (Later Systems)

Later hydramechanical protective systems have hydraulic circuits that use check valves to hold hydraulic pressure on (lock) the fuel rack shut-off actuator in the "shut-off" position after the engine has stopped. In this system, the start-up override valve must be operated to release the hydraulic pressure from the rack shut-off actuator before the engine can be started. Also, the air inlet shut-off must be manually opened before the engine is started.

Make reference to the schematics for the explanation that follows of the hydramechanical protective system hydraulic circuits. The operation of the hydraulic circuits are the same as that of the earlier hydraulic circuits except for the check valves in the rack shut-off circuit.

SCHEMATIC NO. 13 (START-UP OVERRIDE)
1. Selector valve. 2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 7. Diverter valve. 8. Rack shut-off actuator. 10. High speed oil protection valve. 15. Rack sequence valve. 17. Oil Pump. 19. Remote normal shut-off valve.

Start-Up Override Of Oil Pressure Protection

Make Reference to Schematic No. 13

On hot restart, after severe operating conditions, the engine oil pressure is relatively slow to build up. If the rate of pressure rise is too slow, the protective system senses this is a fault condition and moves the fuel rack control linkage to the shut-off position. Therefore, an override of the low oil pressure protective circuit is included in the protective system.

Depending on the type of starter motor used, a solenoid or air operated start-up override valve (3) is installed in the diverter valve return line. The valve is normally closed. When valve (3) is operated, the outlet of the diverter valve is connected to drain. The rack shut-off actuator line is also connected to drain. This maintains a pressure drop across orifice (4) and does not let the diverter valve shift to the shutdown position.

When valve (3) is not in use, the oil protection circuit is restored.

SCHEMATIC NO. 14 (LOW OIL PRESSURE FAULT)
1. Selector valve. 2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 6. Speed sensing valve spool. 7. Diverter valve. 8. Rack shut-off actuator. 10. High speed oil protection valve. 15. Rack sequence valve. 17. Oil pump. 19. Remote normal shut-off valve.

Low Speed Range (Oil Pressure Fault)

Make Reference to Schematic No. 14

If the engine oil pressure goes below 140 kpa (20 psi), the spring force on valve (2) will close the valve. The oil flow in the circuit is then blocked and cannot flow to drain. The pressure of the oil will become equal on both sides of orifice (4). Spring force will move the valve spool of diverter valve (7) down so that there is alignment with the passage that leads to fuel rack shut-off actuator (8). Oil pressure will now move the fuel rack shut-off actuator, which will move the rack control linkage to the "OFF" position. The start-up override valve (3) must be operated to release the rack shut-off actuator hydraulic pressure before the engine can be started.

SCHEMATIC NO. 15 (REMOTE NORMAL SHUT-OFF)
3. Start-up override. 4. Diverter valve orifice. 7. Diverter valve. 8. Rack shut-off actuator. 19. Remote normal shut-off valve.

Remote Normal Shut-Off

Make Reference to Schematic No. 15

An air or electric operated remote normal shut-off valve (19) is installed in the diverter valve return line. When valve (19) is operated, the outlet of the diverter valve is blocked. The oil pressure becomes equal on both sides of orifice (4). Spring force will move the valve spool of diverter valve (7) to make an alignment of the oil passage with the oil line to fuel rack shut-off actuator (8). Oil pressure can now move the fuel rack shut-off actuator, which will move the fuel rack control linkage to the "OFF" position.

The start up override valve (3) must be operated to release the rack shut-off actuator hydraulic pressure before the engine can be started.

2301 Nonparallel Control System

NONPARALLEL CONTROL BOX

The 2301 Nonparallel Control gives exact engine speed control. The system measures engine speed constantly and makes necessary corrections to the engine fuel setting through an actuator connected to the fuel system.

The engine speed is felt by a magnetic pickup. As the teeth of the flywheel go through the magnetic lines of force around the pickup an AC voltage is made. The ratio between the frequency of this voltage and the speed of the engine is directly proportional. An electric circuit inside the control box feels the AC voltage. In response it sends a DC control voltage, inversely proportional to engine speed, to the actuator.

The actuator is connected to the fuel system by linkage. It changes the electrical input from the control box to mechanical output that changes the engine fuel setting. For example, if the engine speed was more than the speed setting, the control box will decrease its output and the actuator will decrease fuel to the engine.

The rated and low idle speeds are set with speed setting potentiometers. An optional remote speed trim potentiometer will give ± 6% speed setting adjustment. A capacitor can be used between terminals 15 and 16 to control the amount of time it takes the engine to go from low idle to rated speed. An oil pressure switch is connected between terminals 9 and 10. This switch is normally open. When the engine oil pressure increases to 6.4 ± 2.7 psi (44 ± 19 kPa) the switch closes. This permits the control to accelerate the engine to rated speed. If the oil pressure decreases to 3.9 ± 3.3 psi (27 ± 23 kPa) the control will return the engine to low idle.

ACTUATOR

MAGNETIC PICKUP

The gain and stability potentiometers control the response of the engine to a change in load. The gain potentiometer is used to decrease response time to a minimum. The stability potentiometer is used to get the best speed stability for the gain setting that is used.

A droop potentiometer can be connected between terminals 13, 14 and 15 to control the amount of speed droop. Droop is necessary when paralleling with a utility bus or a unit with a hydra/mechanical governor.

The speed failsafe circuit will return the voltage output of the control to zero if the magnetic pickup signal has a failure. This will cause the actuator to move to the FUEL OFF position. Also the engine will not start if the magnetic pickup signal has a failure.

NOTE: On the 8N408 Control Box a jumper must be added between terminals 3 and 4 to deactivate the failsafe circuit for test purposes.

WIRING DIAGRAM FOR 2301 NONPARALLEL CONTROL BOX

For more information, make reference to Special Instruction Form No. SEHS7367.

2301 Parallel Control System

2301 PARALLEL CONTROL BOX

The 2301 Parallel Control has two functions: exact engine speed control and kilowatt load sharing. The system measures engine speed constantly and makes necessary corrections to the engine fuel setting through an actuator connected to the fuel system.

The engine speed is felt by a magnetic pickup. As the teeth of the flywheel go through the magnetic lines of force around the pickup an AC voltage is made. The ratio between the frequency of this voltage and the speed of the engine is directly proportional. An electric circuit inside the control box feels this AC voltage. In response its sends a DC control voltage, inversely proportional to engine speed, to the actuator.

The actuator is connected to the fuel system by linkage. It changes the electrical input from the control box to mechanical output that changes the engine fuel setting. For example, if the engine speed was more than the speed setting, the control box will decrease fuel to the engine.

Kilowatt load sharing between a group of engine driven generator sets is made possible by electric circuits in the control box. The load on each generator in the system is measured constantly by its control box. Loads are compared between control boxes through paralleling wires between all the units on the same bus. From the input of the paralleling wires the load sharing circuits make constant corrections to the control voltages sent to the actuators. This gives kilowatt load sharing.

The rated and low idle engine speeds are set with speed setting potentiometers. An optional remote speed trim potentiometer will give ± 4% speed setting adjustment. The ramp time potentiometer controls the amount of time it takes the engine to go from low idle to rated speed. An oil pressure switch is connected between terminals 14 and 15. This switch is normally open. When the engine oil pressure increases to 6.4 ± 2.7 psi (44 ± 19 kPa) the switch closes. This permits the control to accelerate to rated speed. If the oil pressure decreases to 3.9 ± 3.3 psi (27 ± 3 kPa) the control will return the engine to low idle.

WIRING DIAGRAM FOR 2301 PARALLEL CONTROL BOX

ACTUATOR

MAGNETIC PICKUP

A minimum fuel switch can be connected between terminals 22 and 23. This gives an optional method for shutdown. When this switch is closed the voltage output to the actuator is zero.

The gain and stability potentiometers control the response of the engine to a change in load. The gain potentiometer is used to decrease response time to a minimum. The stability potentiometer is used to get the best speed stability for the gain setting that is used.

The speed droop potentiometer controls the amount of speed droop. It can be set between 0 and 13%. Droop is necessary when paralleling with a utility bus or a unit with a hydra/mechanical governor.

NOTE: Potential Transformer and current transformers must be connected for speed droop to function.

The de-droop potentiometer gives compensation during isochronous operation for droop caused by component tolerances and outside electrical noise. Make adjustments after equipment installation is complete.

The load gain potentiometer is set so that the ratio between the actual kilowatt output and the rated kilowatt output of each unit in the system is the same.

The speed failsafe circuit will return the voltage output of the control to zero if the magnetic pickup signal has a failure. This will cause the actuator to move to the FUEL OFF position. Also the engine will not start if the magnetic pickup signal has a failure.

NOTE: On the 8N409 Control Box the jumper between terminals 29 and 30 must be removed to deactivate the speed failsafe circuit for test purposes.

On the 8N408 Control Box terminals 12 and 13 are used for either 24V or 32 VDC. Terminals 25 of all the units in parallel, are connected together in series. This gives a high voltage selection of all battery voltages. Selection of the high voltage as the common supply to all units prevents small speed changes caused by different battery supply voltages.

For more information, make reference to Special Instruction Form No. SEHS7368.

Automatic Start/Stop System - (Non-Package Generator Sets)

AUTOMATIC START/STOP SYSTEM SCHEMATIC (Hydraulic Governor)
1. Starter motor and solenoid. 2. Shutoff solenoid. 3. Fuel pressure switch. 4. Water temperature switch. 5. Oil pressure switch. 6. Overspeed contactor. 7. Battery. 8. Low lubricating oil pressure light (OPL). 9. Overcrank light (OCL). 10. Overspeed light (OSL). 11. High water temperature light (WTL). 12. Automatic control switch (ACS).

An automatic start/stop system is used when a standby electric set has to give power to a system if the normal (commercial) power supply has a failure. There are three main sections in the system. They are: the automatic transfer switch, the start/stop control panel (part of switch gear) and the electric set.

Automatic Transfer Switch

The automatic transfer switch normally connects the 3-phase normal (commercial) power supply to the load. When the commercial power supply has a failure the switch will transfer the load to the standby electric set. The transfer switch will not transfer the load from commercial to emergency power until the emergency power gets to the rated voltage and frequency. The reason for this is, the solenoid that causes the transfer of power operates on the voltage from the standby electric set. When the normal power returns to the rated voltage and frequency and the time delay (if so equipped) is over, the transfer switch will return the load to the normal power supply.

AUTOMATIC TRANSFER SWITCH

AUTOMATIC START/STOP SYSTEM SCHEMATIC (2301 Control System)
1. Magnetic pickup. 2. Starter motor and solenoid. 4. Oil pressure switch 1 (OPS1). 5. Water temperature switch. 7. Overspeed switch. 8. Battery. 9. Low lubricating oil pressure light (OPL). 10. Overcrank light (OCL). 11. Overspeed light (OSL). 12. High water temperature light (WTL). 13. Automatic control switch (ACS). 14. EG-3P Actuator. 15. 2301 Control box. 16. Oil pressure switch 2 (OPS2).

Control Panel

The main function of the control panel is to control the start and shutoff of the electric set.

AUTOMATIC START-STOP CONTROL PANEL
1. Overcrank light (OCL). 2. Low lubricating oil pressure light (OPL). 3. Overspeed light (OSL). 4. Automatic control switch (ACS). 5. High water temperature light (WTL).

The engine control on the automatic start-stop control panel is an automatic control switch (ACS) with four positions. The positions of switch (4) are: OFF/RESET, AUTO, MAN and STOP. Each light (1), (2), (3) and (5) goes ON only when a not normal condition in the engine stops the engine. The light for the condition in the engine that stopped the engine is ON even after the engine has stopped. Switch (4) must be moved to the OFF/RESET position for the light to go OFF. Each light will go ON, for a light test, when the light is pushed in and held in.

When the generator is to be used as a standby electric power unit, the automatic control switch is put in the AUTO position. Now, if the normal (commercial) electric power stops, the engine starts and the generator takes the electric load automatically. When the normal (commercial) electric power is ON again, for the electric load, the circuit breaker for the generator electric power automatically opens and generator goes off the electric load. After the circuit breaker for the generator opens, the engine automatically stops.

When the automatic control switch (ACS) is moved to the MAN position, the engine starts. It is now necessary for the circuit breaker for the generator electric power to be closed manually. If the generator is a standby electric power unit and the automatic control switch (ACS) is in the MAN position when normal (commercial) electric power is ON again, the generator circuit breaker opens and the engine stops automatically the same as when the switch (ACS) is in the AUTO position.

The engine will stop with the automatic control switch (ACS) in either the AUTO or MAN positions if there is a not normal condition in the engine. The not normal condition in the engine that can stop the engine is either low lubricating oil pressure, high engine coolant (water) temperature or engine overspeed (too much rpm). When any of these conditions stops the engine, the light for the not normal condition will stay ON after the engine is stopped. The fourth not normal condition light is ON only when the starter motor runs the amount of seconds for the overcrank timer (engine does not start).

Move the automatic control switch (ACS) to the OFF/RESET position and the not normal condition lights goes OFF.

Electric Set

The components of the electric set are: the engine, the generator, the starter motor, the battery, the shutoff solenoid and signal switches on the engine. The electric set gives emergency power to drive the load.

An explanation of each of the signal components is given in separate topics.

Wiring Diagrams

The following wiring diagrams are complete to show the connections of the automatic start/stop components with the engine terminal strip (TS1). The diagrams show all available options for both the hydraulic governor application and the 2301 Control System application.

For a more complete explanation of operation of the automatic start/stop system, refer to Floor Standing Switch gear Form No. SENR7970.

WIRING DIAGRAM FOR AUTOMATIC START-STOP SYSTEM (Hydraulic Governor Application)
1. Magnetic switch. 2. Flywheel. 3. Magnetic pickup. 4. Terminals (on electronic speed switch). 5. Circuit breaker. 6. Battery. 7. Starter motor. 8. Oil pressure switch. 9. Pressure switch with time delay. 10. Water temperature contactor. 11. Shutoff solenoid. 12. Air shutoff solenoids. 13. Synchronizing motor for UG8 Governor. 14. Engine terminal strip 1.

WIRING DIAGRAM FOR AUTOMATIC START-STOP SYSTEM (2301 Control System Application)
1. Magnetic switch. 2. Flywheel. 3. Magnetic pickup. 4. Terminals (on electronic speed switch). 5. Circuit breaker. 6. Battery. 7. Starter motor. 8. Oil pressure switch. 9. Pressure switch with time delay. 10. Water temperature contactor. 11. Air shutoff solenoids. 12. EG Governor actuator. 13. Engine Terminal strip 1.